1. Field of the Invention
The present invention relates generally to an industrial gas turbine engine, and more specifically to inlet air cooling of the compressor in the engine.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
An industrial gas turbine engine is used in a power plant to generate electrical power. A nuclear power plant may use an industrial gas turbine engine to produce power during peak loads so that the nuclear reactors can operate without reducing power during low loads. Many variables affect the overall efficiency of a gas turbine engine. One of these variables is for the inlet air temperature of the engine. The lower the air temperature passing into the compressor of the engine, the higher will be the efficiency. With the rising price of the fuel used in the combustor, improving the engine efficiency is necessary to keep costs low.
One process for increasing the efficiency of a gas turbine engine is to cool the turbine inlet air prior to compressing it in the compressor. This pre-cooling causes the air to have a higher density and thereby creating a higher mass flow rate through the turbine. a higher mass flow rate through the turbine will produce more power in the turbine and therefore increase the overall efficiency of the engine.
Various processes have been proposed for pre-cooling the compressor inlet air in the gas turbine engine. one prior art reference, U.S. Pat. No. 6,470,686 B2 issued to Pierson on Oct. 29, 2002 and entitled SYSTEM FOR CHILLING INLET AIR FOR GAS TURBINES, discloses the use of an air chiller at the inlet to the compressor along with a process for chilling water that is pumped through the chiller to act as a heat exchanger for cooling the inlet air. The tank that stores the chilled water is located onsite and requires the input of energy to cool the water that is used in the chiller.
U.S. Pat. No. 5,390,505 issued to Smith et al on Feb. 21, 1995 entitled INDIRECT CONTACT CHILLER AIR-PRECOOLER METHOD AND APPARATUS discloses a power plant with a gas turbine engine that produces electrical power, where the inlet air for the engine is cooled by using ice. In a diurnal system, a cooling mass, such as ice, is generated and stored during one cycle, which cooling mass is then available for reducing the temperature of a contacting coolant fluid. This cooling-mass-generating cycle in the exemplary generator illustration may occur during an off-peak demand period, such as the night time, which minimizes the cost of generating the cooling mass (ice) as the cost of electrical power is usually lower for commercial users during the off-peak hours. See column 17, lines 9-18. In the Smith et al invention, the ice is formed close to the power plant.
What is needed in the art of industrial gas turbines used for power production is a process for cooling the compressor inlet air that requires less energy to provide the cooling that the cited prior art references.